1. Field of the Invention
The present invention relates generally to apparatus and methods for inserting vascular catheters into blood vessels. More particularly, the invention relates to the construction and use of a guiding sheath for selectively directing such catheters into particular blood vessels.
A wide variety of non-invasive angioplastic methods exist for removing obstructions from blood vessels. Generally, these methods rely on the peripheral introduction of a catheter to the site of the obstruction and the manipulation of the catheter in some manner to remove the obstruction. The most common method employs a balloon-tipped catheter which is inflated at the site of the obstruction to dilate the passage therethrough. Also, laser catheters are used to ablate obstructions and certain catheters are then provided with cutting implements to excise the obstructions.
One difficulty with such angioplastic techniques has been the ability to properly locate the catheter within the patient's vascular system. In particular, difficulties arise whenever the arteries branch (bifurcate) and the catheter can proceed down the incorrect blood vessel.
Heretofore, catheters have generally been located by using a guidewire having a spring tip which is bent so that the direction of insertion can be selected by rotating the wire. The catheter is then inserted over the guidewire to the proper location. Alternatively, some catheters have an integral spring tip which is used to guide the catheter in an analgous manner.
The use of such guidewires and spring-tipped catheters, however, is not always satisfactory. In particular, placement of catheters into the superficial femoral artery (SFA) from the common femoral artery (CFA) has proved problematic. Because of the location of insertion and the angles at which the two arteries deviate, it can be very difficult to direct the guidewire into the superficial femoral artery.
For the above reasons, it would be highly desirable to provide apparatus and methods for the improved placement of catheters and guidewires within the vascular system. In particular, it would be desirable to provide an insertional sheath which can facilitate the directing of guidewires and spring-tipped catheters at branches within the vascular system, such as the bifurcation of the common femoral artery and the superficial femoral artery.
2. Description of the Background Art
U.S. Pat. Nos. 4,484,585 and 4,601,701 disclose catheters having multiple axial lumens with multiple lateral ports. Neither patent teaches the use of such a device as an insertion sheath. A double lumen cannula for hemodialysis is disclosed in U.S. Pat. No. 4,493,696. Insertional sheaths for catheters are described in U.S. Pat. Nos. 3,459,184 and 4,306,562. See also U.S. Pat. Nos. 3,670,729; 4,252,122; and 4,586,926 which relate to various insertional needles and catheter guides.
Dr. C. Cope of the University of Pennsylvania has developed an insertional catheter which provides for selective insertion of catheters into arteries. The insertional catheter is described in U.S. Pat. No. 4,405,314.